With a small grove the difficulty in using pesticides is compounded. During periods of high demand, it can be difficult to get one of the limited number of professional pesticide applicators to treat your trees. They can make more money by staying in a larger grove, thus reducing time spent traveling and setting up, not to mention the increased liability and regulatory responsibility for having more customers.
As the grower you are responsible for obtaining a Site ID number from the county Ag Commissioner and for submitting the Pesticide Use Report at the end of the month in which any pesticide is used.
An Agrimek application by helicopter in San Diego county requires a non-sprayed 'buffer zone' of 75 feet from houses, and 150 feet from any aquatic features (ponds, streams, etc.). On some properties this leaves very few trees that can be treated. By ground application the buffer zone is 25 feet from the above mentioned features.
Currently the only material that can be sprayed during bloom, when bees are foraging, is Veratran-D, the weakest of the three materials. See Veratran-D for more information on this material.
The only thing available easily and without restriction are lacewings. We have used these predators since 1999 and they have provided economical control of the thrips except in years of very heavy pest pressure, such as in 2005. We recommend the release of 10,000 per acre every other week until the fruit are about 3/4 inch long. This will cost approximately $42.00 per acre per release or about $252.00 per acre for the pest season, which runs from April through the end of June.
If you use the lacewings we strongly recommend that you continue to count thrips on the leaves and fruit; consider spraying if the thrips count exceeds 4 to 5 per leaf or the number of infested fruit exceeds 20%. If the lacewing are unable to maintain the pest population below damaging levels, they may buy you some time to get a spray application lined up before a substantial percentage of your fruit is scarred.